The present invention relates to a transfusion device for feeding, by selecting a drug and designating quantity and rate of transfusion, its transfusion solution through pressurization, which is used as an intravenous infusion device or the like for drip.
Generally,in a known transfusion device, an intermediate portion of a transfusion tube having one end coupled with a drug solution bag and the other end coupled with an injection needle is set and transfusion solution (drug solution) in the transfusion tube is fed through pressurization by driving, for example, a linear peristaltic pump so as to be infused into a body of a patient.
Meanwhile, it is not desirable that air is mixed into drug solution infused into the body of the patient. When size of air bubbles in the drug solution is minute or quantity of air bubbles in the drug solution is small, air bubbles in the drug solution are permissible to some extent. However, when size and quantity of air bubbles in the drug solution exceed predetermined values, undesirable influences are exerted upon the body and in some cases, risk of life of the patient is incurred.
Therefore, in the known transfusion device of this kind, a bubble sensor is generally provided such that a processing against a malfunction is performed when air bubbles are detected in the drug solution.
FIGS. 23(a) and 23(b) show a conventional bubble sensor BS2 in which a pair of ultrasonic sensors 110 and 120 are provided on an outer peripheral surface of a transfusion tube 100 so as to be spaced a predetermined distance X from each other in a direction of flow of transfusion solution. The first ultrasonic sensor 110 is constituted by an ultrasonic transmitter 110s and an ultrasonic receiver 110r and the ultrasonic transmitter 110s and the ultrasonic receiver 110r are brought into contact with the outer peripheral 10 surface of the transfusion tube 100 so as to confront each other in a radial direction of the transfusion tube 100. In the second ultrasonic sensor 120, an ultrasonic transmitter 120s and an ultrasonic receiver 120r are likewise provided on the outer peripheral surface of the transfusion tube 100 so as to confront each other in the radial direction of the transfusion tube 100.
When transfusion solution (drug solution) 200 flows through the transfusion tube 100 relative to an ultrasonic path connecting the ultrasonic transmitter and the ultrasonic receiver, ultrasonic wave is propagated sufficiently, so that reception level of the ultrasonic receiver is high and thus, output of the ultrasonic transmitter exceeds a predetermined level. However, when an air bubble 300 is mixed into the transfusion solution 200 in the transfusion tube 100 as shown in FIG. 23(a) and passes through the ultrasonic path, propagation rate of ultrasonic wave drops greatly, thereby resulting in extreme drop of output level of the ultrasonic receiver. Mix of the air bubble 300 into the transfusion solution 200 is judged by detecting this extreme drop of output level of the ultrasonic receiver. Thus, when outputs of both of the ultrasonic receivers 110r and 120r of the first and second ultrasonic sensors 110 and 120 have dropped to low levels, it is judged that the air bubble 300 having a size larger than the distance X between the ultrasonic sensors 110 and 120 has been detected. In this case, drive of the peristaltic pump is stopped and an alarm or a warning display is given.
Meanwhile, in the known transfusion device, transfusion has been performed by setting drug in the transfusion device in accordance with indications such as prescription prior to transfusion and manually inputting data on quantity, rate and period of transfusion, etc. In another prior art transfusion device, the transfusion device and a controller for the transfusion device are connected to each other by a communication circuit such as a telephone circuit such that commands on quantity, rate and period of transfusion, etc. are set via the communication circuit.
In the case of the above mentioned bubble sensor BS2 of the known transfusion device, size of the air bubble 300 to be detected by the bubble sensor BS2 is determined by the distance X between the ultrasonic sensors 110 and 120. However, since the distance X between the ultrasonic sensors 110 and 120 is specific to the bubble sensor BS2, a lower limit of size of air bubbles capable of being detected by the bubble sensor BS2 is fixed at a predetermined value. Therefore, size of air bubbles to be detected by the bubble sensor BS2 cannot be adjusted arbitrarily according to patients ranging from adults to children and thus, the bubble sensor BS2 should be replaced for each patient.
Furthermore, as shown in FIG. 23(b), in case air bubbles 300a and 300b are, when passing through the bubble sensor BS2, separated from each other but are, after passing through the bubble sensor BS2, united with each other to a size requiring stop of the pump and the warning display, outputs of the ultrasonic receivers 110r and 120r do not become low levels simultaneously when the air bubbles 300a and 300b pass through the bubble sensor BS2. Therefore, the bubble sensor BS2 is set to an undetected state and thus, there is a risk that the body of the patient is adversely affected by the air bubbles 300a and 300b. Meanwhile, in case a malfunction of the transfusion tube 100 occurs upstream of the bubble sensor BS2 and air bubbles are mixed into the transfusion solution gradually, the small air bubbles cannot be detected by the bubble sensor BS2 when an operator continues to perform transfusion for a long time without noticing the malfunction. Thus, as a result of transfusion performed for a long time, there is a risk that a more harmful influence is exerted on the body of the patient.
In addition, the known bubble sensor is large in size due to the need for the two sets of the ultrasonic sensors.
Meanwhile, in the prior art transfusion device, there is a risk that when drug is set in the transfusion device, a wrong drug may be selected due to an error of an operator. Furthermore, erroneous data on quantity, rate and period of transfusion may be manually inputted by the operator.